Dissecting aneurysm of superior cerebellar artery. Its association with fibromuscular dysplasia

Distal Parent Vessel Occlusion of 2 Superior Cerebellar Artery Fusiform Aneurysms: Report of 2 Cases and Literature Review

Background

Fusiform superior cerebellar artery (SCA) aneurysms are rare, and their management represents a technical challenge. In complex aneurysms, endovascular parent vessel occlusion of the SCA may be a treatment option. Here, we present 2 cases of fusiform SCA aneurysms, 1 ruptured and 1 unruptured, as well as our institution's management with parent vessel occlusion. We also provide a review of the literature.

Cases Description

Case 1: A 42-year-old male was transferred from an outside hospital with subarachnoid hemorrhage. On admission, the patient had a Glasgow Coma Scale score of 8, a Hunt and Hess grade 4, and a Fisher grade 4. A diagnostic angiogram demonstrated a right SCA fusiform lesion with proximal and distal dilatations of 1.45 mm and 5.35 mm long, respectively, likely representing a single dissecting pseudoaneurysm. The distal dilatation was coiled, resulting in parent vessel occlusion. The patient recovered clinically and was discharged in stable condition.

Case 2: A 27-year-old female was transferred from an outside hospital due to a brainstem stroke. A diagnostic angiogram revealed an S2/S3 segment left SCA fusiform lesion, likely representing a dissecting aneurysm. The patient was neurologically intact at admission and managed conservatively. At the 2-month follow-up angiogram, the dissection had extended along the length of the SCA. Consequently, the patient underwent coil embolization of the distal left SCA. At the 6-month follow-up, the vessel remained obliterated and the patient's neurologic status had improved.

Conclusions

Endovascular coil embolization of fusiform SCA aneurysms offers a reasonable and safe treatment approach.

A Study on the Clinical and Angiographic Spectrum of Spontaneous Extracranial Dissections in the Cerebral Vasculature

Aim:

To prospectively study the clinical profile, angiographic features, and functional outcomes, in consecutive cases of extracranial dissection seen at two tertiary stroke care centers in South India.

Materials and Methods:

In this observational study, spanning 4 years (December 12–December 16), a total of 442 patients presented with an acute ischemic stroke/transient ischemic attack (TIA) at our study centers. 14/546 (3.2%) of these patients had magnetic resonance angiography (MRA)/computed tomography angiography (CTA) evidence of extracranial dissections. All cases underwent detailed clinical evaluation on arrival, and data were recorded on a predesigned stroke pro forma. Contrast MRA was done on arrival in all cases as part of a standard stroke protocol, and CTA was done only if MRA was inconclusive. The pattern of the vessel involved and morphology of vessel dissection was analyzed as per a standard radiology protocol. All the cases were managed with short-term anticoagulation using low-molecular-weight heparin followed by oral anticoagulants for 3–6 months. All cases were followed up for 1–2 years and the functional outcomes were recorded using the modified Rankin Scale (mRS).

Results:

There were 11 males and 3 females in the study, and the mean age was 45.1 years (range = 27–65 years). Focal neurological symptoms occurred in all these patients (10 patients had a stroke, and 4 had TIA). Nearly 64.2% of these (9/14) were stroke in young (age <45 years). The internal carotid artery was the most common vessel involved in 85.7% (12/14) cases. Of the ten patients with completed stroke, a good functional outcome (mRS 1–2) was seen in 8/10 (80%). Digital subtraction angiography and revascularization procedures were needed only in a minority of cases 3/14 (21%).\

Conclusion:

This hospital-based study highlights the importance of suspecting arterial dissections in young strokes of unexplained etiology, and offering optimum anticoagulant therapy in the acute phase, to achieve good long-term outcomes.

Epidemiology, pathophysiology, diagnosis, and management of intracranial artery dissection

Spontaneous intracranial artery dissection is an uncommon and probably underdiagnosed cause of stroke that is defined by the occurrence of a haematoma in the wall of an intracranial artery. Patients can present with headache, ischaemic stroke, subarachnoid haemorrhage, or symptoms associated with mass effect, mostly on the brainstem. Although intracranial artery dissection is less common than cervical artery dissection in adults of European ethnic origin, intracranial artery dissection is reportedly more common in children and in Asian populations. Risk factors and mechanisms are poorly understood, and diagnosis is challenging because characteristic imaging features can be difficult to detect in view of the small size of intracranial arteries. Therefore, multimodal follow-up imaging is often needed to confirm the diagnosis. Treatment of intracranial artery dissections is empirical in the absence of data from randomised controlled trials. Most patients with subarachnoid haemorrhage undergo surgical or endovascular treatment to prevent rebleeding, whereas patients with intracranial artery dissection and cerebral ischaemia are treated with antithrombotics. Prognosis seems worse in patients with subarachnoid haemorrhage than in those without.

Fusiform superior cerebellar artery aneurysm treated with STA-SCA bypass and trapping

BACKGROUND

Fusiform aneurysms of cerebellar arteries are rare. Different surgical techniques to address these challenging lesions have been described, and their application depends on whether the goal is to maintain the flow in the parent vessel or to occlude it.

CASE DESCRIPTION

The authors reported a case of a fusiform aneurysm located in the lateral pontomesencephalic segment of the superior cerebellar artery (SCA) in a 32-year-old man who presented with subarachnoid hemorrhage. The patient was subjected to aneurysm trapping followed by a bypass between the superficial temporal artery (STA) and SCA and had an uneventful recovery.

CONCLUSIONS

Although only a few cases of fusiform aneurysms in the supracerebellar artery have been reported in the literature, the treatment strategies adopted were diverse. In selected cases of patients in good neurological condition with ruptured fusiform aneurysms at the proximal segments of SCA and who have poor evidence of collateral supply, the possibility of a STA-SCA bypass with aneurysm trapping must be considered. A review of the current treatment modalities of this pathology is also presented.

Fibromuscular Dysplasia of Cervical and Intracranial Arteries

Fibromuscular dysplasia is an uncommon, segmental, nonatherosclerotic arterial disease of unknown aetiology. The disease primarily affects women and involves intermediate-sized arteries in many areas of the body, including cervical and intracranial arteries. Although often asymptomatic, fibromuscular dysplasia can also be associated with spontaneous dissection, severe stenosis that compromises the distal circulation, or intracranial aneurysm, and is therefore responsible for cerebral ischaemia or subarachnoid haemorrhage. Fibro-muscular dysplasia affects middle and distal portions of the internal carotid and vertebral arteries, and occasionally, intracranial arteries. Several pathological and angiographic patterns exist. The most frequent pathological type is medial fibromuscular dysplasia, which is associated with the ‘string of beads' angiographic pattern. Unifocal lesions are less common and can be associated with several pathological subtypes. The pathophysiology of the disease is widely unknown. Fibromuscular dysplasia may in fact result from various causes and reflect a non-specific response to different insults. The poor knowledge of the natural history and the lack of randomised trials that compared the different treatment options do not allow any satisfactory judgement to be made regarding the need for or the efficacy of any treatment.

Dissection of the superior cerebellar artery: a report of two cases and review of the literature

Arterial dissections frequently involve the main trunk of the posterior circulation and are recognised as an important cause of stroke in young individuals. However, dissection confined to cerebellar arteries is rare. We encountered two patients with superior cerebellar artery (SCA) dissection. A 37-year-old man presented with dysarthria, right limb ataxia, and severe headache. Magnetic resonance imaging revealed cerebellar infarction in the right SCA territory. Angiography demonstrated stenosis and fusiform dilation of the SCA in the anterior pontine segment. Recovery with antiplatelet treatment was nearly complete. A 45-year-old man was admitted with decreased consciousness after sudden onset of headache. Computed tomography demonstrated subarachnoid haemorrhage with hydrocephalus. Angiography revealed fusiform dilation of the left SCA in the anterior pontine segment. After ventricular drainage, endovascular embolisation was performed without ischaemic complications. The patient's condition improved sufficiently to return to daily life. In our search only four reported cases involved the SCA. Clinical manifestation and treatment for patients with cerebellar arterial dissections are discussed.

Cerebellar infarction in the territory of the superior cerebellar artery in children

Posterior circulation infarction is uncommon in children. Vertebral artery dissection is an unusual cause of posterior circulation infarction in children. We report on a 12-year-old boy with spontaneous left-extracranial vertebral artery dissection associated with isolated ipsilateral superior cerebellar artery territory infarction, diagnosed clinically and by brain computed tomography, magnetic resonance imaging, and magnetic resonance angiography. Cerebral angiography demonstrated a flame-like occlusion of the left vertebral artery at level C(2)-C(3), and indicated that artery-to-artery embolus may be a mechanism of superior cerebellar artery territory infarction. We emphasize that vertebral artery dissection should be considered in a child with acute signs of posterior circulation ischemia.

Fusiform aneurysm of the superior cerebellar artery: short review article

Fusiform superior cerebellar artery (SCA) aneurysms are quite rare and only 9 cases have been reported in the literature. Fusiform aneurysms are a small group of cerebral aneurysms among the most difficult to treat. The therapeutic approaches in the limited number cited in the literature include surgery and endovascular occlusion. Surgical techniques which have been used are parent artery occlusion, trapping or body clipping of the bleeding site, and wrapping for fusiform aneurysms. Neurological condition, presence of collateral circulation, type and configuration of the aneurysm, and type of the dissection are important factors that predict the course of fusiform SCA aneurysms. We reviewed the literature on fusiform aneurysm of the SCA and report a further case treated surgically.

Vertebral artery dissection from neck flexion during paroxysmal coughing

Vertebral artery dissection has a characteristic presentation that should be considered when symptoms are preceded by any trauma that causes neck movement. We present the case of a man with vertebral artery dissection following severe coughing that presented as a postero-inferior cerebellar artery territory stroke. The patient was anti-coagulated, and his neurologic deficits were partially resolved. The mechanism and presentation of vertebral artery dissection are discussed with an emphasis on early detection.

Benign arterial dissections of the posterior circulation

Four young adults with spontaneous dissection of the vertebrobasilar system are reported. Clinically, two patients presented with subarachnoid hemorrhage and two with brain-stem ischemia. In two cases of ruptured arterial dissection of the posterior cerebral artery, angiography demonstrated fusiform and "sausage-like" dilatation of the involved vessel. In two cases of occlusive dissection of the basilar artery, angiography revealed the typical "string sign." All four patients were treated conservatively: three survive in good clinical condition and one remains disabled. Follow-up angiograms showed spontaneous healing of the lesion with return to an almost normal arterial configuration in two cases; residual narrowing corresponding to the dissection was the most notable finding in the other two. It is recommended that, in a subset of neurologically stable patients, angiographic monitoring is undertaken to assess the tendency for spontaneous repair before surgical intervention is planned.

Arterial pathology in cerebellar infarction

We reviewed 88 pathologically proven cerebellar infarcts, examining the entire thoracocervical arterial system (including the spinal part of the vertebral artery, the intracranial arteries, and the heart) in all cases. For 50 infarcts, we found an arterial occlusion. The intracranial part of the vertebral artery was involved in 38 infarcts (76%), the basilar artery in 20 infarcts (40%), and a cerebellar artery in 12 infarcts (24%). Eight infarcts were due to bilateral distal vertebral artery occlusions. For the 50 infarcts, the cause of the occlusion was atherosclerosis in 28 (56%) and a cardiac embolism in 12 (24%). For the remaining 38 infarcts, we found no arterial occlusions on postmortem examination. Of these 38 infarcts, 26 (68%) were associated with a cardiac source of emboli. For the entire group of 88 infarcts, atherosclerosis was the cause in 31 (35%), while a cardiac embolism was proven or presumed in 38 (43%). Dissecting aneurysms, atherosclerotic artery-to-artery embolism, or hemodynamic mechanisms could have been responsible for a few infarcts. We conclude that cerebellar infarcts often arise from cardiogenic embolism.

Etiologic factors in renovascular fibromuscular dysplasia. A case-control study

The role of several factors that have been suggested as being of etiologic importance in renovascular fibromuscular dysplasia was examined in a case-control study of 33 patients with angiographically demonstrated fibromuscular dysplasia and 61 renal transplant donor control subjects with normal renal arteries. The factors studied included use of oral contraceptive agents or markers of sex hormone dysfunction, mechanical stress to the renal artery wall, human lymphocytic antigen (HLA) type, cigarette smoking, history of hypertension for more than 5 years, and family history of cardiovascular disease. The risk of fibromuscular dysplasia was significantly (p = 0.003) increased (odds ratio = 4.1, 95% confidence interval = 1.5-10.9) among cigarette smokers. A significant (p less than 0.001) dose-response relation was noted between cigarette use and the risk of fibromuscular dysplasia developing (odds ratio = 8.6 for those who had smoked more than 10 pack-years). Personal history of hypertension more than 5 years was also associated (odds ratio = 5.0, 95% confidence interval = 1.1-22.8) with a significantly (p = 0.036) increased risk for the development of fibromuscular dysplasia. HLA-DRw6 antigen was more common in the 33 fibromuscular dysplasia patients than in the 61 renal transplant donor control subjects (odds ratio = 3.00, p = 0.067) or a second group of 934 ambulatory control subjects (odds ratio = 2.51, p = 0.031). Adjustment for cigarette smoking increased the odds ratio to 5.0 (95% confidence interval = 1.3-19.6). There was a positive though not statistically significant (odds ratio = 1.7, p = 0.175) association noted between family history of cardiovascular disease and fibromuscular dysplasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Superior cerebellar artery infarction and vertebral artery dissection

Isolated superior cerebellar artery infarction is rare, and the mechanism is often not readily apparent. We describe a patient with an isolated superior cerebellar artery infarction resulting from an ipsilateral vertebral artery dissection. Angiography demonstrated intraluminal clot in the superior cerebellar artery, suggesting artery-to-artery embolus as a mechanism of this uncommon stroke syndrome.

Arterial fibromuscular dysplasia

Fibromuscular dysplasia is a nonatherosclerotic, noninflammatory vascular disease that involves primarily the renal and internal carotid arteries and less often the vertebral, iliac, subclavian, and visceral arteries. Although its pathogenesis is not completely understood, humoral, mechanical, and genetic factors as well as mural ischemia may play a role. The natural history is relatively benign, with progression occurring in only a minority of the patients. Typical clinical manifestations are renovascular hypertension, stroke, subarachnoid hemorrhage, abdominal angina, or claudication of the legs or arms. In patients with symptoms, percutaneous transluminal angioplasty has emerged as the treatment of choice in most involved vascular beds.

Reticular fiber deficiency in the intracranial arteries of patients with dissecting aneurysm and review of the possible pathogenesis of previously reported cases

The pattern of reticular fibers in the tunica media of the major intracranial arteries was investigated in two patients with dissecting aneurysm. In numerous circumscribed areas, the reticular fibers were absent close to the internal elastic lamina in all major arteries of each patient. It is suggested that the subintimal deficiency in reticular fibers results in insufficient fixing of the tunica intima to the media contributing to their separation when the internal elastic lamina becomes defective. The presumed etiologies of the previously reported cases are reviewed and the possible origin of the deficiency in reticular fibers is discussed.

Intracranial dissecting aneurysms of the posterior circulation. Report of six cases and review of the literature

Dissecting aneurysms of the intracranial posterior circulation are unusual lesions that affect otherwise healthy young adults, are difficult to diagnose and manage, and carry a high morbidity and mortality rate. Headache in the suboccipital-posterior cervical region is the most common presenting symptom. The dissection usually occurs between the intima or internal elastic lamina and the media; subadventitial dissection does occur and accounts for the infrequent finding of subarachnoid hemorrhage. A deficit in the inner layers of the vessel is the proposed source of dissection. The angiographic features are inconsistent, although an irregularly narrowed arterial segment with proximal and/or distal dilatation are typical findings. Depending on the location of the dissection, the surgical options are: ligation, trapping, or reinforcement of exposed abnormal portions of the vessel. Anticoagulation therapy is not indicated in the management of this lesion.